1. Field of the Invention
The present disclosure relates to methods for the characterization of kidney function. Several embodiments relate to the diagnosis of kidney disease and more specifically, the present disclosure relates to the field of characterizing by quantifying kidney-related RNA contained in vesicles to characterize kidney function.
2. Description of Related Art
In many cases, physicians interpret a patient's symptoms, medical history and the results of a physical exam to derive an initial diagnosis. Medical tests are an integral part of confirming or modifying an initial diagnosis. Currently, some diagnostic medical tests are performed on blood extracted from a patient to determine disease from a biochemical pattern that is not present in healthy patients or is altered from a previously obtained patient sample. These tests commonly utilize plasma or serum and measure, for example electrolytes, urea, creatinine, and glucose. Other tests measure plasma proteins such as albumins, immunoglobulins, fibrinogens, and regulatory proteins. Still other tests measure other biological compounds, such as, for example, thiamin, riboflavin, niacin, vitamin B6, folic acid, vitamin D, biotin, iron, and clotting factors factor V and factor X.
Similarly, in the context of evaluating kidney function, measurement of the plasma concentrations of waste substances that should be removed by a functional kidney (such as creatinine and urea) or concentrations of electrolytes are often made to determine renal function. However, blood urea and creatinine levels often will not be raised above the normal range until a substantial amount (e.g., 40% or greater) of total kidney function is lost. Evaluation of glomerular filtration rate (GFR) or clearance of pharmacological marker compounds can also be used to evaluate kidney function. Analysis of 24 hour urine samples can also be used to evaluate kidney function. Another prognostic marker for kidney function is proteinuria, an elevated level of protein in the urine. Increasing amounts of proteins (such as albumin) in the urine indicate progressively increasing amounts of kidney damage, and associated loss of function.
However, these diagnostic tests are typically antibody based tests, commonly an ELISA, which may have limitations with respect to sensitivity. The combination of questionable assay accuracy at low assay target concentration ranges with the presumably low levels of creatinine (or other assay target) in the early stages of disease make it possible that diagnosis in early disease stages is not made. Additionally, certain diagnostic tests employ chemical reactions (e.g., colorimetric changes) to identify markers from blood or other fluid samples. Such tests may also be affected by similar limitations as are described above. Thus, there exists a need for a sensitive, accurate and reproducible diagnostic test for evaluating kidney function that enable early detection and/or diagnosis of compromised kidney function.